Glass choppers use fluid or electric powered blade rotors to break continuous glass rovings into individual short glass fiber lengths. These choppers use a hard rubber back up roll as an anvil which cooperates with a rotor carrying one or more transversely extending blades. The back up roll and rotor cooperate to chop a discrete glass fiber length off the continuous roving each time a rotor blade contacts the back up roll.
OSHA Standard 1910.212 provides in pertinent part:
(1) One or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips and sparks. Glass choppers typically satisfy this requirement with a cover that encloses the bladed rotor and back up roll. The cover also includes a discharge chute which directs chopped glass fibers away from the operator. Typically, the cover is held in place on a stud extending from the chopper body by a nut captive to the cover. This nut often is difficult to turn, and inspection of equipment usually shows damage from pliers used to turn the nut. Ordinarily, the stud used to, fasten the cover to the chopper body also supplies auxiliary purge fluid for the chopper. PA1 This standard does not apply to (a) work on cord and plug connected electrical equipment for which exposure to the hazards of unexpected energization of start up of the equipment is controlled by the unplugging of the equipment from the energy source and by the plug being under the exclusive control of the employee performing the servicing or maintenance.
OSHA Standard 1910.147 relates to control of hazardous energy during servicing or maintenance of machines such as glass choppers. This regulation has been interpreted to be intended to provide the same measure of protection for the operator while servicing, maintaining and adjusting the equipment as the machine guarding regulations provide. During operation of a glass chopper, it is frequently necessary to clean and adjust the chopper. When this is done the operator is required to go the primary source of the energy powering the chopper, shut the energy off, bleed any stored excess energy and affix a lock for which only he or she has the key that prevents restoring the power to the chopper until the lock is removed.
Standard 1910.147, Section (a)(2) (iii) states:
This regulation has been interpreted as excluding similar fluid powered equipment provided the energy stored is bled and the plug is removed. In order for the energy stored to be bled when the plug is removed, there must be no valves between the unplugged fitting and the motor.
Typical glass choppers have no easily accessible fitting which allow this unplugging. Further, servicing of the chopper can be done without unplugging the power source. Thus, it is easy for the operator to circumvent the protection provided by the cover.